The plate beckoned. Jacoby Ellsbury, creeping farther off third base as Andy Pettitte delivered his second pitch to J.D. Drew, saw the situation clearly. The pitcher was throwing from the windup, the lefthander's back to third base, the third baseman playing off the bag, the bases loaded.

So on the next pitch, Ellsbury was three-quarters of the way down the line before Pettitte noticed him, the pitch coming as fast as he could throw it to catcher Jorge Posada. Ellsbury was coming, too, then sliding, head-first after a brief stumble, as Drew stood watching. Posada's tag was futile.

Ellsbury had stolen home in the fifth inning, the highlight of the Red Sox' 4-1 win last night and a series sweep of the Yankees.

The roar was deafening, even though the crowd of 38,154 at Fenway Park seemingly was having trouble realizing what it had just seen. This was better even than his tear for home from second base on a wild pitch in his rookie season, the one that made them think he was a god on the base paths. It was simply brilliant.

And Pettitte had never even looked over.

"I've never seen anyone attempt it, let alone somebody actually do it," said Jason Bay, who was on deck. "I got a really good view of it. That's something I won't forget. That's the last thing you're ever expecting, and all of a sudden you've got Ells, who flies, just takes off, and everything's kind of happening at once. I'm thinking, 'Jeez, J.D., don't swing.' And boom, he slid in."

It might not have been the difference in the game, but the play was emblematic of a series in which the Sox got the better of the Yankees at every point. There was the home run with two down in the ninth on Friday, and the homer that won it in extras, the thrashed New York bullpen Saturday, and the steal of home last night, all culminating in a sweep that is the crowning touch on a 10-game winning streak.

Starting with Tim Wakefield's near no-hitter against Oakland, the Sox have gone from faltering to dominating, their 2-6 record turned into 12-6. The team has yet to prove itself on the road, but the Sox get a chance to show their momentum extends outside city limits when they start a nine-game road trip tonight in Cleveland.

"I was actually like, 'Does everyone realize? I don't know how many 9-0 homestands you guys have been a part of, but I know I haven't been a part of many,' " said Bay, the veteran of years with the Pirates. "It doesn't really surprise me. It doesn't seem as if we're on this improbable roll. Just we're going out there, we're winning ballgames, doing the things we should do to win."

The Sox have done nearly everything right in this streak. There was Ellsbury's steal of home, but it was more than that. Justin Masterson continued to show his value with another short-but-sweet start. The front office and manager Terry Francona looked brilliant with the one-day call-up of Michael Bowden, as Hunter Jones and Bowden combined on a perfect eight outs before yielding to Takashi Saito. And the panic began in New York.

"I don't want to get too carried away with what happened this homestand because when we're 2-6, the big thing we talk about is staying in the moment," Francona said. "I think that's the best way to have success is not think about last week. But it was a good homestand for us. That's stating the obvious. And much-needed."

After all the insanity of the first two games of the series, all the runs and late-inning home runs, one was left wondering whether the Sox and Yankees actually could play a normal game. Perhaps Kevin Youkilis taking grounders at shortstop in batting practice was as crazy as this one was going to get.

Then came Ellsbury, the steal yielding to a curtain call and undoubtedly producing today's round of "Did you see that?" in workplaces in New England and beyond. He got put in a good-natured headlock by his manager, and got a whole lot of high-fives from teammates. It was the first steal of home for the Sox since Jose Offerman on a double steal Aug. 30, 1999, and the first straight steal of home by the Sox since Billy Hatcher April 22, 1994.

"I guess this is the point where I sit up here and tell you I got here at 11 o'clock this morning, and pored over reports, and I'm a very smart manager," Francona said. "What we have is a very fast player with some guts."

"Sometimes I get in that zone where I lock everything out," said Pettitte, who had the same thing happen to him with Aaron Hill in a game against Toronto in 2007. "[Posada] just told me to keep an eye on him. I saw Ellsbury out of the corner of my eye. I didn't think he'd be able to steal home. I figured if he took off I would run through my windup and get him out at home. The bottom line is that I didn't run through my windup fast enough to get the ball home fast enough obviously to get him."

And Drew made the ongoing at-bat worth his while, bringing home David Ortiz on a ground-rule double to put the Sox ahead by the eventual final score.

The steal might have been a shock, but one thing was definite. For Masterson, this was going to be more than a reliever-acting-as-starter night. Not just because it was Sox-Yankees, or because it was an ESPN game, but because the Sox had bullpen worries. Ramon Ramirez wasn't going to pitch. Neither was Manny Delcarmen. Or Jonathan Papelbon.

And though he stumbled slightly in the third, allowing a run when Hideki Matsui singled then came around on a Brett Gardner sacrifice fly, he was far more efficient and far better at his task than Josh Beckett had been the day before. He got through 5 1/3 innings, throwing 99 pitches, and left the game to Jones with the Sox ahead by three.

"He was terrific," Francona said. "He attacked the strike zone. He changed speeds. I thought he had good depth on his slider, threw a couple changeups, got his fastball by a couple guys."

Then he headed out of the game. The Yankees went quietly from there, a whimper to finish an absolutely electric series for the Red Sox, an electric homestand, an electric winning streak.

"Everyone's excited, obviously," second baseman Dustin Pedroia said. "Any time you go [undefeated] on a homestand, we've been playing good baseball. So our biggest thing is get back on the road, and play a lot better than we did last road trip."